Да ну? валидный все!

Цитирую artur:

Чтобы Jre Cache правильно работал нужно установить права доступа 666 на след. файлы :
/index.php
/administrator/index.php
Потом увидите как помимо index.php будут созданы indexj.php

мануал по исталу с оф.сайта -

Installation of the component is simple. You can install the component through the Joomla installer, but make sure that the /index.php and the /administrator/index2.php files of your webserver has the permissions to be overwritten by the patch file (set the permission on 666) and make also sure that your root directory of your website (the location where the index.php is) and the root of the administrator directory is also writeable.
In the installation process the orginal index.php file in your webserver root is copied to jindex.php and the administrator/index2.php is copied to administrator/jindex2.php then the cache component will install the cache index.php file and the administrator/index2.php file. These files will included the original index.php file and the administrator/index2.php file.

If you get a permission error at installation time you can install the component simply by your self with a FTP program. Therefor perform the following steps:

1. rename your /index.php file into /jindex.php
2. copy the /administrator/components/com_jrecache/install_files/index.php to /index.php file
3. rename your /administrator/index2.php file /administrator/jindex2.php
4. copy the /administrator/components/com_jrecache/install_files/index2.php to /administrator/index2.php file

After installation you will need to "enable" the cache through the configuration panel. When you enable the cache make sure that the 'default' settings are correct. For example the component uses the default location of your website configuration file, but if this is located on a different location due to security reasons correct the path in the configuration setting.

ithin the Administration panel you can administrate the behauviour of the cache repository.

SQL/DB Error -- [You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 1]
как это решить?

скажите пожалуйста, почему после удаления версии 3.0 у меня перестал открываться сайт, следовательно я не могу не загрузить новую, ни вообще открыть админку